Weighing scale



Feb. 6, 1945. R. M. FRAPS WEIGHING fscALE Filed June 21 1943 4 Sheets-Sheet 1 I INVENTOR- R. ".FRAPS LJ MLLLML ATTORNEYS Feb. 6, 1945.

R. M. FRAPS WEIGHING SGAL E Filed June 21, 1943 4 Shets-Sheet 2 INVENTOR R. M.FRAPS ATTORNEYS Feb. 6, 1945. R. M. FRAPS 2, 8

WEIGHING SCALE Filed June 21, 1943 4 Sheets-Sheet 5 INVENTOR R.M.FRAPS ATTORNEYS Feb. 6, 1945. R. M. FRAPS 2,368,655

WEIGHING SCALE Filed June 21, 1943 I 4 Sheets-Sheet 4 I'i;5.Z

4o (3) i 0 95 f /A so (4): 115 I3 85 o 140 E -110 i so 15H as 1 INVENTOR 8o R. M. FRAPS ATTORN EYS Patented Feb.;6, 1945 UNITED STATES: PATENT OFFICE ffifim lmuflti'lil lfllii $111111? Lia '3Claims. (crass-74st (Granted under the act of March 3,1883, as amended April 30, 1928; 870 0. G. 7571 \v This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described, if patented, may be manufactured and used by or for the Government of the United States of America. for governmental purposes without the payment to me of any royalty thereon.

My invention relates to weighing scales, and more particularly to weighing scales employing a movable index line optically projected over the face of a-screen bearing scale' graduations.

In conventional types of even balance scales, both full sensitivity and maximal effective range of the scale are not ordinarily realized in the same construction. An extension of range is sometimes accomplished by the use vofmanually applied counterweights in combination with additional chart columns. However, this arrangement is cumbersome, and the several columns of figures composing the chart are a source of confusion unless additional means are employed to block out all columns except the one proper to the capacity range for the applied counterweight or counterweights.

In most laboratory and technical operations, it is essential to realize the greatest possible sensitivity at minimal capacity ranges, since the relative error of weighing operations is generally of greater significance than the absolute error. If a given maximal capacity is desired in a scale,

the simplest means of increasing readability at lower capacity ranges is to increase, directly or indirectly, the length of chart, but in doing so an equal or greater scale sensitivity must be maintained. In the present invention, the base or pri- 'mary chart range may be so limited as to realize thehighest chart readability consonant with the sensitivity of a given construction, higher capac-' ity ranges being attained by multiples of this base or primary chart and capacity range.

One object of this invention is to provide means for the rapid, semi-automatic application and removal of counterweights at fixed positions,

andsochosen as to produce the desired multiplication of the basic chart range, this range oi readability at lower capacity weighings.

A further object is to provide means for thei automatic change of chart ranges simultaneously with the applicationv and/or removal of counterweights to the end that those chart values proper to the sum of applied counterweights at a given setting are before the operator to the exclusion of the maximal number of counterweight and chart sequences theoretically attainable with a given number of counterweights applied at fixed positions, successive capacity ranges being understood as multiples of the base capacity range, that is, the range of the scale with no counterweights applied. v

A further object is to provide means for locking the counterweight and chart mechanism in ,being limited. in order to obtain a high degree fixed and proper positions corresponding to the definite number of available scale ranges, and the provision of positive signals operative in conjunction with the locking device to eliminate all possibility that the operator may take chart readings except when chart and counterweights are in known and proper positions.

Other objects and advantages inhering in this invention will become evident from the following description.

My invention is illustrated by the accompanying drawings, in which:

Figure 1 is a perspective view of a weighing scale embodying my invention;

Figure 2 is a plan view with the housing removed on the line 2-2 of Figure 1;

Figure 3 is a vertical section on the line 33 of Figure 1;

Figure 4 is a vertical section on the line 4-4 of Figure 2;

Figure 5 is a section on the line 5-5 of Figure 1 showing the scale screen assembly in plan;

Figure 6 is a schematic representation of the cams used in the counterweight shifting mechanism; and

Figure 7 is a plan of the endless ribbon scale chart cut and viewed in the plane of the paper.

Similar numerals refer to similar parts throughout the several views.

The weighing scale is mounted on a base It, and

is enclosed by ahousing h on which a hood l2 is hinged. A glass window I3 through which scale readings can be observed is arranged in the hood l2.

The scale mechanism comprises a rectangular frame-like scale beam [4 supported substantially midway of its length by bearings l5 carried in a fulcrum standard 16 which is mounted on the weight alignment cones a, 24, and 25. The outriding beam elements It and II and superimposed elements are maintained in proper alignment by the usually disposed connecting links 28, 21, and II, which form the appropriate parallelogram in conjunction with the beam ll.

The ends of the beam ll are securely attached to opposed weight resistant elements 28, which in turn are dated rigidly with respectto the beam fulcrum l8 through the blocks 30 to the base l0. Extending from the counterweight end of the scale beam is a ,clevis-headed screw it, which carries the adjustable counterpoise 32 and which also-is connected through the clevis to the link a which extends to the usual elements in the dashpot l4.

The capacity end of the beam carries a sidewardly projecting indicator element 85 in which a fine hair or equivalent is disposed horizontally at right angles to the longitudinal axis of the scale beam N. In spaced relation with the indicator element N is a light source II, the lens system 31, and the reflecting mirror 38 held by the adjustable bracket a. The'light source IS, lens 31, indicator 3!, and mirror II are in alignment lengthwise and to the right side of the base ll, as is also that portion of the scale screen 40 hearing the scale graduations. In operation, movement of the beam ll due to applied load displaces the optical beam indicator II vertically and thereby changes it position on the mirror a. from which by reflection of lighted areas the indicator line is displaced on the scale screen ll as a shadow parallel with the scale graduations. The arrangement of the optical system is such that displacement of the indicator line over the fixed scale graduation; is proportional to the load applied to the commodity platter 20, a condition which may be satisfied by proper curvature in the reflecting mirror 38 or by other means known and practiced.

The main scale elements described up to this point, with the exception only of. the counterweight alignment cones II, N, and I! and their supporting base 22 are merely illustrative of construction known to those skilled in the art, and are intended to serve for the clearer presentaa,ses,ess

proportional to the motion imparted to the driving wheel 58.

In its operative alignment the scale chart 52 lies immediately beneath the scale screen 40, and immediately to the left of that portion of the screen which bears the fixed scale graduations. The portion of the screen 4|! directly above the scale chart 52 is opaque except for translucent blocks or spaces placed in the screen 40 so that the numerals of a particular scale chart array will be visible when properly positioned. The arrays of chart numerals proper to given counterweight sums and corresponding capacity ranges appear in these block to the exclusion of all other chart numerals.

The scale chart 5! provides, as illustrated, for eight consecutive capacity ranges which (again by way of example) are 0-20, 20-40 140-160 grams (or units). The scale chart 52 is accordingly subdivided into eighths of it length and capacity range bases 0, 20 140 are designated in correspondence with counterweight sums applied simultaneously as hereinafter described. These bases are indicated in Figure 7 opposite the figures in parentheses (l), (2) (8) to the right of the ribbon chart. From a given base, the remaining numerals of the array are laid oil at distance equal to the distance between major scale divisions. Proceeding similarly, the arrays corresponding to other capacity bases are laid off on the ribbon, completing the chart as shown. The array for the capacity base tion of the elements of my invention which follow.

In the following description, the embodiment of my invention in the form required by an eight-place chart and counterweight mechanism is taken as a suiiicient example of its application, without implying limitation respecting its application generally.

The endless ribbon scale chart and counterweight assemblies are carried by brackets ll and 42, respectively. A control knob ll positioned externally on the right side of the housing I l engages a shaft 44 which is supported in bearings ll and 45 carried in the brackets ll and 42. A bevel gear 41 carried on the shaft 44 engages a bevel gear 48 on a counterweight cam shaft ll, which shaft is supported in bearings 50 and I carried in the bracket 2. As illustrated, the' bevel gears 41 and are in the ratio 1:2, so that the shaft ll will revolve twice while the counterweight cam shaft ll revolves once.

The endless ribbon scale chart 52 is carried over a driving wheel 58 secured to the shaft 44 and over a free pulley 54, which revolves on bearing ll of bracket. Lugs 55 circumferentially located on the driving wheel II engage perforatime I! in the endless ribbonscale chart 5!, in-

80, comprising the numerals 80, 85, 90, 95, 100. is indicated by dotted lines in Figure 7, and is shown in operative position in Figure 1.

With a proper arrangement of the multiple arrays comprising a scale chart of the type described here, all numerals may be equally and closely spaced and the maximal usefulness of a chart of minimal length may thus be attained. Also, this makes it possible to hold the operative mechanism within reasonable limits. For example, with ilxed scale graduations on scale screen 40 covering 4.5 inche and an eight-fold capacity range, the scale chart 5! need be only 15 inches in length with centers of driving wheel "and free pulley 54 separated by about 5.5 inches. Such a chart is, nevertheless, the equivalent, in total range, of a fixed chart 36 inches in length.

If in certain constructions longer ribbon charts are desired than are possible between a single driving wheel and a single free pulley, additional free pulleys may be provided to take care of the additional chart length in a compact manner.

The portion of the scale screen 40 beneath which the ribbon chart 52 travels is illuminated by light from a small bulb 5! inside a suitable shield is. The shield 58 is designed so that diffuse light illuminates the figures of the scale chart 5! which are in operative position but the portion of the scale screen 40 bearing the scale graduations is shielded from the bulb 58, that portion of the scale screen 40 being illuminated only by light from the indicator-light source 38 reflected by the mirror 38. Alternatively, suitable means may be employed to utilize light from the indicator light source 38 for illumination 'of the a screen apertures through which the chart numer- 52 in the present construction is twice the cirluring absolute displacement of the scale chart 1s als are observed.

The length of the endless ribbon scale chart cumference of its driving wheel II. Since the distance between successive capacity bases is A of the scale chart length, successive turns of the a given capacity range.

Again, capacity base indicia or the spaces prop- 1 2,666,666 control knob 46 bring consecutive bases (and corresponding arrays) into the open blocks of the scale screen 46. Successive chart arrays are positioned quickly and positively by means of a lug 66 carried on a spring element 6| which causes it to bear against the rim of a positioning wheel 62 andtoengage positioning seats 66 spaced at 90 intervals on the circumference of the positioning wheel 62. The positioning wheel 62 is fixed on the chart shaft 44 and is thus rotated with thecontrol knob 46 and the chart driving wheel 66.

When the positioning wheel 62 is so set that one of its seats 63 is in engagement with lug 66, and

the chart base 0 or (1) appears in the space adjacent to the base graduation line 64, successive chart bases (and chart arrays) will be properly positioned as successive seats 66 are brought into engagement with the lug 6 6 as the positioning wheel 62 rotates.

Although engagement of the lug 66 with seats 66 of the positioning wheel 62 may be readily perceived during rotation of the control knob 46, supplemental means are provided to eliminate or minimize the possibility that scale readings may be taken with chart numerals other than those designating proper chart arrays before the observer. A contact breaker 66 is so interposed in the circuit supplying the scale screen bulb 66 that this bulb is lighted only when the lug 66 rests within one of the seats 66 of the positioning wheel 62. Identification of the capacity range proper to a given load is of course completed only when the optically projected index shadow (or other spaces, appears in one of the screen apertures, indicating improper setting.

The counterweight mechanism is operated by the control knob 46 simultaneously with the a scale chart 62, the cam shaft 46 turning through a single revolution during the course of two revolutions of "the scale chart shaft 44. The cam shaft 46 carries the three earns 66, 61, and 66,

they are retained in accurate alignment for posi-'-- tioning on these cones.

Sumcient downward motion is arranged for the counterweight levers 66, 16, and 1|, to assure that the annular seats 14 are not in contact either with the oounterweights 16, 16, and 11 or the scale beam I4 at any point in the travel of the beam when counterweights are in applied position; similarly, the counterweights 15, 16 and 11 4 are raised sufficiently when they are free of the receiving cones 26, 24, and 26 to eliminate contact between counterweight and cone during motion ofthe beam 14 through its full traverse. To

- prevent accidental displacement of the counterpointer generally) comes to rest within the limits of fixed scale graduations on the scale screen Alternative constructions may be employed to indicate positively to the operator the correctness of chart array and disposition of counterweights. The scale chart 62 may carry, for example, a continuous marginal portion made opaque except-for properly spaced and preferably narrow apertures which come successively into correspondence with a fixed similar aperture in an otherwise opaque marginal portion of the scale screen 46 as chart bases, but not other indicia, are brought'into apposition with the base scale graduation 64. When, and only when, apertures in the scale chart 62 and the scale screen 46 are in correspondence, light from an interior source, for example, from the light sources 66 or 66, illuminates or is visible through the fixed screen aperture, indicating a proper setting for er to such indicia (0, 20 140 in the example previously followed) may be differentially colored, the appearance of such a differentially colored index or background against the fixed base scale graduation 64 signifying proper setting for given capacity range. In yet another example, regularly spaced segmentstof the scale chart 62, each equal in chart length to thesegment of the chart required-for index numerals, maybe left vacant and preferably colored differentially. The blank space may, for example, be that immediately above each capacity base (1), (2) indicia being laid out in the manner described for charts without suchspaces. tings of the positioning wheel all apertures in the scale screen 46 are occupied by the numerals proper to a true chart array, no blank space ap- .(8), the remainder of the chart At correct setweights 16, 16, and 11 when they are free of the beam l4, spring members 16, extending from the bracket 42, bear upon the heads of counterweights whenthese are free of their cones.

The cams required for the eight-fold capacity range operating simultaneously with the eightplace ribbon chart previously described are schematically shown in Figure 6. Only three cams are required if the ratios of applied counterweights are powers'of 2, that is, 1:224, or as in the present illustrative example, 20, 40, and 80 grams. The requisite cams 66, 61, and 66 are assigned to counterweights 16, 16, and 11, re-

spectively, as indicated in Figure 6.

Eights radial positions, spaced from adjacent positions, are designated for each cam by the radii, l, 2 6, in Figure 6. Similarly designated radial positions are understood to be in axial alignment when the earns '66, 61, and 66 are in operative adjustment on the cam shaft 46. It should be understood also that when the counterweightlevers 66, 16,and 1l ride the lesser radii of the cams 66,61, and 66, the corresponding counterweights 16, 16, and 11 are applied to pearing; at any other setting a blank space, differentially coloredand patently dissimilar from the scale beam l4; and when the counterweight levers ride the greater radii of the cams, the corresponding counterweights are freeof the scale beam.

With radial position 1 of each cam bearing against its respective counterweight lever, as is indicated in Figure 6, all counterweights are free of the scale beam l4, the chart range of 0-20 grams is onthe scale screen 46, and loads within this range are indicated directly on the fixed scale graduations. If, now, the counterweight cam shaft 46 is rotated in a clockwise direction by 45 of a revolution), radial position 2 of each camcomes into play: the 20 gram counterweight 16 is applied to its receiving cone 24, but the 40 and 80 gram counterweight levers 66 and 1| continue to ride the outer radii of their cams. Since the required 45 rotation of the counterweight cam shaft 46 is given by a rotation of the control knob II and the scaleshaft It, the scale chart SI is displaced irom its former position by ,5 of its length, thus bringing into view the proper chart numerals for the capacity range 20-40 grams, (2) in Figure 7. By clockwise rotation of the cam shaft 40 through an additional 45, radial position 3 of each cam becomes effective; the 20 gram counterweight II is lifted from the beam ll, the 40 gram counterweight 11 is almultaneously deposited on its receiving cone 2!. and the 80 gram counterweight It continues to ride free of the beam II. The capacity range is s,see,ess

than those actually offset by the capacity weights are properly counterweighted. In other variations the scale chart may be adapted to provide a plurality of designated over-under" chart indicia, these appearing before the operator simultaneously with the application or removal of the counterweight load required for the indicated terweights from the scale beam, bringing up again radial position 1 with simultaneously the return of chart numerals 0-20 upon the scale screen. 1

The detailed relations involved in'the manipulation of three counterweights of weights 20, 40, and 80 grams in conjunction with chart capacity ranges of the same order are set iorth below in table. It isparticularly to be emphasized that successive positions of the counterweight cams II,

II, and I. and the scale chart I! are realized simultaneously by rotation of the control knob I through 90' intervals, and precisely correct positions are likewise indicated for both counterweight cams and chart arrays by resistance ofv the positioning lug 00, in conjunction with illumination of the chart numerals only when the positioning lug II and consequently the counterweight cams are precisely positioned.

Tabla-Disposition of counterweight: of 20, 40 and 80 grams (or units) in consecutive com positions and for the total capacity range 0-160 0mm by cram increments oi counter- Counter- Chart weights 1 w ht w on "are." 40 80 '0 0-1) 20 M i g 00-80 80 $400 i 100 100-120 I m ill-140 140 140-100 0 0-20 'lhenumberedampoeitions 1,2 srei'ertothepositionsso d ated in Figure 0. The in parentheses (degreespeler to rotat of same from itial itions indicated in lanes. l The gus sign (-t) signifies that e indicated oounterwe ht is app the and the minus sign signifies that the counterweight so designated is free of the sale beam.

While the elements and combination oielements comprising this invention have been described in a convenient embodiment, it is. not intended that this limitation shall be considered in any sense inherent in the application of the invention. In the foregoing description, for example, it has been assumed that the counterweights are carried by an outrider element so disposed that the applied counterweight sum is accurately elective against capacity loads of the same magnitudes. However, the combination of elements embodied in this specified application is equally applicable to a construction'employing a secondary beam, or other disposition of the wtriderelemsnts so that greater or lesser loads this invention. The chart and counterweight mechanisms are applicable directly to simple balances, as for example, the analytical balance, in which application counterweights of calculated values may be operative with reference to differing fixed positions on the beam or suspended from the beam, the effective values of counterweights maintaining in either case the ratios of the binary number system and manipulated synchronously with a ribbon scale chart, or as a limiting case, a cylindrical dial, recording unambiguously the applied counterweight sums. In combination with the "chainomatic" balance, for example, all of!- setting loads above the limit of the chain may be applied as counterweightsand the sum read directly as the sole indicia of the chart visible to the operator at a given setting.

In certain constructions the ribbon scale chart may preferably carry only a part of scale indicia, the recurrent indicia being fixed in or on the scale screen in apposition to either major or minor scale graduations. This arrangement of scale indicia is of particular usefulness where capacity ranges are multiples, directly or indirectly, or a decimal base and small diil'erences in indicated, chart values are desired. In yet another contemplated application of this invention, two or more ribbon scale charts may be ranged parallel to each other and rotated at differential rates to bring before the observer, at defined and fixed positions, the capacity range proper to a given counterweight sum.

It may be pointed out, in connection with various applications which may appear at first sight to be unduly complicated. that with effective counterweight values taken always in ratios of powers of 2, only 4 counterweights are required for 16 consecutive multiples of a base range, and only 5 for multiplication of the base range 32 times. It is obvious that such. multiplications of a given base capacity range would be of small value without means for the absolute identification of counterweight sums, which means are adequately provided by the ribbon scale chart or charts forming a part of this invention.

Having thus described my invention, I claim:

1. A weighing scale comprising a scale beam, a fulcrum support for said scale beam, a capacity platter mounted on one end of said scale beam, a series of counterweights mountable on the other end of said scale beam, the effective weights of said counterweights increasing in the ratio of serial powers of 2. means for disposing said counterweights on said other end oi said scale beam.

an endless ribbon multiple scale chart, the chart arrays on said scale chart being of equal length, the number of chart arrays being equal to 2,

where n is the number of counterweights, the,

values on said scale chart being in equally spaced positions, and the values in any two consecutive positions on said scale chart being values of difa series of counterweights mountable on the other end of said scal beam, the effective weights of said counterweights increasing in the ratio of serial powers of 2; means for disposing said counterweights on said other end of said scale beam; an endless ribbon multiple scale chart, the chart arrays on said scale chart being of equal length, the number of chart arrays being equal to 2, where at is the number of counterweights, the values on said scale chart being in equally spaced positions except for regularly occurringblank positions, and any two adjacentvalues on said scale chart being values of different chart arrays; means for operative correlation of said scale chart with the application of said counterweights; means cooperating with the blank position on said scale chart for defin the Operative array of said scale chart; and means for optically projecting an index of the position of said scale beam in relation to said scale chart.

3. A weighing scale comprising a scale beam, a fulcrum support for said scale beam, a capacity platter mounted on one end of said scale beam, 9. series of counterweights mountable on the other endof said scale beam, the effective weights of said counterweights increasing in the ratio of the serial powers of 2, means for disposing said counterweights on said other end of said scale beam, an endless ribbon multiple scale chart, the chart arrays on said scale chart being of equa1 length, the number-of chart arrays being equal to 2,

' where n is the number of counterweights, the base values of said chart arrays being spaced on said scale chart at intervals equal to the length of said scale chart divided by the number of chart arrays, the length ofle'ach chart array being greater than the interval on said scale chart between the base values of said'chart arrays but not equal to a multiple of said interval and not greater than 'the length of the longest segment oi said scale chart operatively disposed in a plane surface, and

the distance between Values on said chart arrays being selected so as not to equal any of the following: 1) the interval on said scale chart between the base values of saidchart arrays, (2)

an aliquot part of said interval, (3) a multiple vof said interval, means for operative correlation of said scale chartwith the application of said counterweights, means distinguishing the operative chart array of said scale chart, and means for optically projecting an index of the position of said scale beam in. relation to said scale'chart.

RICHARD M. FRAPS. 

